Ts2631 Endolysin from the Extremophilic <i>Thermus scotoductus</i> Bacteriophage vB_Tsc2631 as an Antimicrobial Agent against Gram-Negative Multidrug-Resistant Bacteria

• Main Authors: Magdalena Plotka, Malgorzata Kapusta, Sebastian Dorawa, Anna-Karina Kaczorowska, Tadeusz Kaczorowski
• Format: Article
• Language: English
• Published: MDPI AG 2019-07-01
• Series: Viruses
• Subjects: lytic enzyme; Peptidoglycan recognition proteins (PGRPs); peptidoglycan; <i>Pseudomonas aeruginosa</i>; <i>Acinetobacter baumannii</i>
• Online Access: https://www.mdpi.com/1999-4915/11/7/657

Bacteria that thrive in extreme conditions and the bacteriophages that infect them are sources of valuable enzymes resistant to denaturation at high temperatures. Many of these heat-stable proteins are useful for biotechnological applications; nevertheless, none have been utilized as antibacterial agents. Here, we demonstrate the bactericidal potential of Ts2631 endolysin from the extremophilic bacteriophage vB_Tsc2631, which infects <i>Thermus scotoductus</i>, against the alarming multidrug-resistant clinical strains of <i>Acinetobacter baumannii</i>, <i>Pseudomonas aeruginosa</i> and pathogens from the Enterobacteriaceae family. A 2&#8722;3.7 log reduction in the bacterial load was observed in antibacterial tests against <i>A. baumannii</i> and <i>P. aeruginosa</i> after 1.5 h. The Ts2631 activity was further enhanced by ethylenediaminetetraacetic acid (EDTA), a metal ion chelator (4.2 log reduction in carbapenem-resistant <i>A. baumannii</i>) and, to a lesser extent, by malic acid and citric acid (2.9 and 3.3 log reductions, respectively). The EDTA/Ts2631 combination reduced all pathogens of the Enterobacteriaceae family, particularly multidrug-resistant <i>Citrobacter braakii</i>, to levels below the detection limit (&gt;6 log); these results indicate that Ts2631 endolysin could be useful to combat Gram-negative pathogens. The investigation of <i>A. baumannii</i> cells treated with Ts2631 endolysin variants under transmission electron and fluorescence microscopy demonstrates that the intrinsic antibacterial activity of Ts2631 endolysin is dependent on the presence of its N-terminal tail.